1. Field of the Invention
The present invention relates to a power delivering apparatus employed in an engine-powered vehicle in which toque developed in an engine of the vehicle is transmitted to wheel axles of the vehicle through the power delivering apparatus.
2. Description of the Prior Art
A power delivering apparatus for transmitting a torque developed in an engine of an engine-powered vehicle to opposite wheel axles of the vehicle is proposed in Japanese Patent Laid-Open No. 186051/1988 (in Japanese, called Tokkaisho 63-186051) which is an unexamined patent publication in Japan.
In the power delivering apparatus proposed in the above unexamined patent publication, the torque developed in the engine of the vehicle is changed in amount in a final reduction gear unit of the vehicle, and, thereafter the torque thus changed in amount is transmitted to the opposite wheel axles of the vehicle. This conventional power delivering apparatus comprises: a differential gear; and a differential-limiting unit such as a viscous coupling for limiting the differential action of the differential gear. As for the differential gear, such gear is necessary so that opposite wheels of the vehicle can rotate different amounts when the vehicle goes around a turn. As this happens, the outside one of the opposite wheels must turn more times that the inside one thereof. The differential gear permit this action while still delivering power to both of the opposite wheels to enable the vehicle to make turns easily. On the other hand, as for the differential-limiting unit such as the viscous coupling, in case that one of the opposite wheels of the vehicle loses traction on muddy or icy roads to cause the vehicle to stick in a muddy or icy spot, the differential-limiting unit prevents the differential gear from transmitting power exclusively to such substantially no-traction wheel, thereby permitting the vehicle to escape from these troublesome spots.
In the vehicle, this conventional differential gear is placed off a longitudinal center line of the vehicle in a width direction thereof, while connected with opposite wheel axles through opposite constant velocity universal joints. Each of the opposite wheel axles comprises: a first axle member extending between the differential gear and the constant velocity universal joint; and a second axle member extending between the constant velocity universal joint and a wheel. In the vehicle having the above construction, in order to make these second axle members equivalent in length to each other, it is necessary to make one of the first axle members longer than the other of the first axle members. Such longer one of the first axle members is splined to a hub of the differential-limiting unit or viscous coupling so that the two must turn together, while supported by a vehicle body through a bearing in the vicinity of the constant velocity universal joint connected with such longer one of the first axle members.
However, in the conventional vehicle having the above construction, since looseness is most likely to occur between the longer one of the first axle members and the bearing or the hub, and since the viscous coupling which is larger in diameter than each of the wheel axles increases such looseness, the viscous coupling is most likely to vibrate noisily when the wheel axles are rotatably driven. This is a problem inherent in the conventional power delivering apparatus.